This research was supported by grants from the NIH (EB-04285, CA-115531, DK-058398, and RR-02584) and the Robert A. Welch Foundation (AT-584).
Journal of the American Chemical Society
Europium -- Magnetic properties, Contrast media (Diagnostic imaging) -- Synthesis, Ligands (Biochemistry), Magnetic resonance imaging, Paramagnetic contrast media
The chemical exchange saturation transfer (CEST) efficiency for a series Eu3+-based tetraamide complexes bearing p-substituents on a single coordinating pendant arm is highly sensitive to water exchange rates. The CEST effect increases in the order Me < MeO < F ∼ CO2tBu < CN ≪ H. These results show that CEST contrast can be modulated by changes in electron density at a single ligating atom, and this forms the basis of creating imaging agents that respond to chemical oxidation and reduction.
Ratnakar, S. J., Woods, M., Lubag, A. J., Kovács, Z., & Sherry, A. D. (2008). Modulation of Water Exchange in Europium (III) DOTA− Tetraamide Complexes via Electronic Substituent Effects. Journal of the American Chemical Society, 130(1), 6-7.